#!/usr/bin/python3

import sys
import string

def file_is_printable(file_):
    result = True
    for lineno, line in enumerate(file_):
        for char in line:
            if char not in string.printable:
                sys.stderr.write('line # {} has unprintable characters\n'.format(lineno + 1))
                result = False
    return result

def main():
    if sys.argv[1:]:
        for filename in sys.argv[1:]:
            with open(filename) as file_:
                if not file_is_printable(file_):
                    sys.exit(1)
        sys.exit(0)
    else:
        if not file_is_printable(sys.stdin):
            sys.exit(1)
        sys.exit(0)

main()